The field of the present invention is the art of ring-type hose clamps that are employed for holding and securing sections of elastomeric tubing in telescoped connection with metal or plastic tubes or pipes. Such devices are frequently employed in the various engine systems of automotive vehicles powered by internal combustion or diesel engines. Such hose clamps find utility in radiator and heater hose attachment, securing of pollution control equipment and attachment of air or breather lines. The most common type of clamp in use today for such applications is the well-known slotted band clamp wherein a screw or worm member has threaded engagement with the slots of a circular band which is received immediately therebelow and in threaded engagement therewith. These devices are exceptionally expensive to manufacture and frequently require a second tightening to effect a tight seal. The end portion of the band may extend a considerable distance beyond the housing and catch on clothing and tools and is unsightly. Another popular wire loop clamp is shown in Anjos et al, U.S. Pat. No. 4,414,715 wherein the end portions of the wire extend a considerable distance from the outer circumference of the hose and present a hazard and source of irritation to installation personnel, as the sharp ends cause cuts to individuals working in the engine compartment and to wiring harness.
Many attempts have been made to design a secure leak-proof form of clamp for hoses utilizing a minimum number of parts which are inexpensive to manufacture. Attention is directed to the ring-clamp of Munse shown in U.S. Pat. No. 3,722,041 of Mar. 27, 1973. In this construction a single length of wire is formed into a circle with the ends bent at right angles outwardly and a screw member is inserted through a hole in one of the ends and is in threaded engagement with the other end. Tightening of the screw will of course serve to tighten the ring around the tube or hose captured therein, but the instability and weakness of such a clamp renders it useless for most applications.
The 1893 Weidaw U.S. Pat. No. 492,855, was an early form of hose clamp utilizing a single piece of wire and a nut and bolt. This arrangement required soldering or brazing the ends of the wire together. A single loop of wire is utilized to receive the screw pilot. Devices of this type have been found to be completely ineffective from a performance standpoint since the wires are placed directly in line. Accordingly, there is a void in the area of engagement where no effective sealing can take place. Further, the pilot end of the screw will serve to penetrate the coiled section and the coiled section which acts as a nut flares outwardly to meet the loops. This arrangement will yield at very low torque.
A somewhat similar arrangement is shown in the Black U.S. Pat. No. 2,349,809 of May 30, 1944, which with slight modifications is presently being used on many automobiles imported from Japan. This construction does not apply adequate pressure at the cross over points of the wire and high screw torque, due to washer friction, thread friction, and the loop cinching against the screw pilot causes the threaded plate to follow the screw rotation. This serves to lift one loop at the cross over point and negates the seal.
Another early simplified hose clamp is shown in Schroeder, U.S. Pat. No. 1,432,572 of Oct. 17, 1922, which utilizes hooked ends extending through an actuating plate. Here a pocket is used to accept the end of the screw. The screw itself is not provided with a pilot point and the wires themselves are below the center line of the screw.
Yet another arrangement is shown in the U.S. Pat. No. 2,561,635 issued to Prochaska on Jul. 24, 1951. This arrangement is quite similar to the Black construction, supra, but requires a single welded loop of wire. Note that the screw center is substantially elevated from the hose.